The present invention relates to heating apparatus particularly adapted for thawing frozen particulate material in railway hopper cars in order to facilitate off-loading of the material.
Particulate material such as coal, coke, iron ore, gravel and sand, or the like, are economically bulk transported in large, open-topped hopper cars from whence they are off-loaded at a point of storage or of use, either from bottom openings in the cars or by means of car dumpers that invert the entire car. Off-loading of such moisture-laden material is rendered difficult in colder climates due to freezing of the load during transit or while standing on the railroad.
Various forms of heating apparatus have heretofore been employed to thaw frozen hopper car loads to permit ready discharge of their contents. Such apparatus have included fuel-fired thawing pits, typified by U.S. Pat. No. 2,598,293, granted May 27, 1952 to Parker, et al, that are located in the rail bed and over which the car to be thawed is positioned. Apparatus of this type is costly to install requiring excavation and shoring of the rail bed. It is also costly to maintain and to operate since the heating pits form receptacles that rapidly accumulate debris which must be constantly cleared in order for the heater to perform effectively.
Other forms of heaters utilized in similar applications include electrically operated radiant heaters, such as those shown and described in U.S. Pat. Nos. 3,513,779, granted May 26, 1970 to Aitken and 3,800,858 granted Apr. 2, 1974 to Placek. Such heaters being electrically operated are extremely costly to operate and require constant maintenance to insure that the heating coils and associated reflective surfaces remain clean.
Units comprising a plurality of small gas heaters employing exposed heat tubes that deliver heat in localized regions have also been tried but these are costly to install and are prone to damage by debris and moisture from the railcars thereby also rendering them costly to maintain.
Several of the aforementioned thawing heater apparatus are further undesirable in that they subject the pneumatic brake hoses and couplings which extend between cars to excessive heat causing deterioration and failure of this equipment resulting in costly repair and replacement.
It is to the amelioration of the aforementioned problems, therefore, that the present invention is directed.